简单的3*3矩阵bmp图像边缘识别，读入bmp图像，按照用户指定的阈值区分边缘，并以黑线白底的图片形式展现-Simple 3* 3 matrix BMP image edge identification, read BMP images, according to the user specified threshold distinguish edge, and in the form of a black line on the bottom of the picture show